How to choose between Spike2 and Signal

There are many similarities between these two. Both can be installed as either 64-bit or 32-bit Windows applications, capable of driving the Power1401 and Micro1401, and signal conditioners such as the CED 1902 and Digitimer D360 range of amplifiers in multi-channel data acquisition. Analysis tools for both programs include averaging and FFT (multi-channel) and Virtual (calculated) channels for cross-channel arithmetic and waveform generation. Both programs have comprehensive menu commands and a powerful script-driven mode of operation.

Generally, experiments involving evoked response with relatively short response latencies will benefit from using Signal. A deciding factor, when choosing between Signal and Spike2, is whether longer term recordings are required. Spike2 can be used as a form of oscilloscope and record both continuous and episodic data, but it lacks the automatic randomisation of stimulus generation which is one of the main features of Signal.

The differences are firstly in the type of data acquisition, secondly in the specialised features.

Data acquisition

Spike2 is designed to collect continuous data: waveforms, digital events and markers, like a very intelligent chart recorder. Waveforms can be captured at independent sampling rates. This enables the system to record experiments that involve low frequency signals such as respiration as well as high frequency signals like nerve activity into a smaller file size than would otherwise be possible.

Signal is designed to capture triggered or un-triggered episodic waveform data, like an oscilloscope. All waveform channels share the same sample rate. With the built-in outputs dialogue it is easy to set up protocols to output stimulus trains and waveforms with changing amplitude and duration for such experiments as LTP, LTD, TMS and patch/voltage clamp. The output protocol can be modified while recording and alternative output protocols selected.

Specialised features

Spike2 has spike shape recognition, spike clustering, digital filtering and many time domain analysis tools, which are useful for analysing and displaying spike trains. Spike2 also features a comprehensive feature detection system which is useful for finding and measuring waveforms such as ECG complexes.

Spike2 is able to produce complex outputs as a combination of waveform and events. These could control switches and motors in, say, a long term behavioural experiment. Video channels can be captured and linked to the data files.

Signal includes support for a range of Transcranial Magnetic Stimulation (TMS) and constant current stimulators. Up to ten stimulators can be controlled simultaneously, and their intensities and stimulus timings automatically changed. Built-in functions for TMS studies include MTAT (PEST) threshold estimation as well as random, semi-random and protocol ordering of stimulus states.

Dynamic clamping using up to 15 independent models is supported at high rates with the Power1401-3 or Micro1401-4. Signal also includes all the tools needed for traditional Patch and Voltage clamping. Single channel data can be analysed using thresholding or the advanced SCAN technique developed by Professor David Colquhoun.